How do Fingerprint Scanners work?

Fingerprint scanners have become a common technology now . Every smartphone now has a fingerprint scanner to unlock the phone. But every time when you move your finger towards the sensor have you ever thought how it works ?
Well stick on to the article to know the technology behind fingerprint scanners.
The main principle here is pattern recognition.There are ridges and valleys in your fingerprints. These ridges and valleys form a pattern which is unique for every individual.Based on the method used to identify the patterns there are basically 3 types of Fingerprint scanners.



Capacitive sensors consists of an array of cells.Each cell consists of conductive plates. So here the patterns are formed by charges stored by the capacitors.

When you place your finger on the sensor the ridges come in contact with the capacitor arrays and that leads to an electric charge that gets stored in the capacitor.These stored charges form a pattern and can be used to identify unique fingerprints
These are widely used nowadays in the smartphones.


These type of scanners use visible light to take a photo of your fingerprints. In this, LEDs are used to illuminate a finger kept on a glass plate. The light reflected from the finger falls onto a Charged-Coupled Device (CCD) present in the scanner. A CCD – also used in camcorders and digital cameras – is basically an array of pixels which respond to falling light over them and generate proportional electrical signals.

The scanning process starts when you place your finger on a glass plate, and a CCD camera takes a picture. The scanner has its own light source, typically an array of light-emitting diodes, to illuminate the ridges of the finger. The CCD system actually generates an inverted image of the finger, with darker areas representing more reflected light (the ridges of the finger) and lighter areas representing less reflected light (the valleys between the ridges).light-emitting diodes, to illuminate the ridges of the finger.


To actually capture the details of a fingerprint, the hardware consists of both a transmitter and a receiver. An ultrasonic pulse is transmitted against the finger that is placed over the scanner. Some of this pulse is absorbed and some of it is bounced back to the sensor, depending upon the ridges, pores and other details that are unique to each fingerprint.

There isn’t a microphone listening out for these returning signals, instead a sensor that can detect mechanical stress is used to calculate the intensity of the returning ultrasonic pulse at different points on the scanner. Scanning for longer periods of time allows for additional depth data to be captured, resulting in a highly detailed 3D reproduction of the scanned fingerprint.

So now when you use your fingerprint to unlock your phone you know how it actually work. If you liked the blog please like and follow.If you have any suggestion feel free to comment or mail us at

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